Darren Criss on his 'How to Succeed' debut and Daniel Radcliffe

Darren Criss can cross “Broadway debut” off his New Year’s resolution list. The 24-year-old Glee star takes over for Daniel Radcliffe in the hit Broadway musical How to Succeed in Business Without Really Trying for three weeks, beginning tonight. (After that, singer Nick Jonas will play corporate-ladder climber J. Pierrepont Finch.) EW talked to the University of Michigan theater major about the show, what this means for his TV gig, and his connection to Radcliffe’s famed Harry Potter role.

Broadway was a no-brainer: After spotting him on Glee,How to Succeed producers Craig Zadan and Neil Meron (Hairspray) thought Criss would be the ideal choice to succeed Radcliffe when the Harry Potter star left the show after 10 months. “We asked Darren if he was interested in doing a limited run in the show, and he got on a plane and snuck into the theater one matinee to check out the part,” says Zadan. “He called when he got out and said, ‘I have to play this role!’” Adds Criss, “It seemed too good to be true, so I made it a priority.”

He’s always been wild about Harry: In college, Criss played the Boy Who Lived in a 2009 spoof called A Very Potter Musical; YouTube clips of his performance soon went viral. But he and Radcliffe have never met. “We have lots to talk about, the least of which would be Harry Potter,” says Criss, adding that they both work with the Trevor Project, a service organization supporting gay and lesbian youth. “We’ve been on parallel paths.”

Fear not, Gleeks: Blaine will be back: Given the postholiday timing of his Broadway gig, Criss will miss only one episode of Glee. Even so, he’s grateful to Glee co-creator Ryan Murphy and the network for granting him a brief sabbatical: “They were surprisingly supportive.”

Opening-night terrors: Criss hopes that friends and family are MIA for his first performance at the Al Hirschfeld Theatre. “Everyone’s like, ‘Oh, I gotta go to your opening night!’ ” he says. “But I’m terrified. I’m like, ‘No! See it at, like, two and a half weeks.’ Theater is a living creature. It takes a while to break in, like a new pair of shoes.”